Ingredients: Old Kay guitar parts, two by four, stainless steel pot, threaded rod for bridge, which is pushed down to bottom of the pot by tension on strings. A little water in the pot.
Many thanks to Bart Hopkin for excellent engineering tips, and of course, to Jacques Dudon for his amazing Aquavina -- inspiration for this project. Something bowed, played on one's lap would still be great (more like the Aquavina), or perhaps more like a cello -- but in this case I'm still struggling a bit with physics. (What? Water has to fall level to the planet? No fair!!)
So starting out, I'm playing it more like a guitar, half lap, half held in the regular way, just not enough to tip the little bit of water out (ideally... I've managed to tip a lot of water out!) with enough water to swirl around, the pot between my knees and not muted. Awkward so far, but very stable holding its tuning. Here's a first sample.